共查询到20条相似文献,搜索用时 15 毫秒
1.
用顺序GISH-FISH 技术鉴定小麦-中间偃麦草小片段易位系 总被引:6,自引:1,他引:6
利用顺序基因组-重复序列原位杂交技术对1个来自中3不育系和普通小麦恢75杂种后代稳定株系H96276-2的染色体组成进行了分析。以中间偃麦草(Agropyronintermedium)基因组DNA为探针的荧光原位杂交结果表明,H96276-2的体细胞中有42条染色体,包括20对小麦染色体和1对小麦-中间偃麦草易位染色体,中间偃麦草染色体的易位片段位于1对小麦染色体的端部。进而用重复序列探针pSc119进行第2次荧光原位杂交,证明H96276-2中的中间偃麦草染色体易位片段位于小麦2B染色体的短臂上。 相似文献
2.
小麦异源易位系的高效诱导和分子细胞遗传学鉴定 总被引:7,自引:0,他引:7
利用杀配子染色体(gametocidal chromosome)和低剂量(10Gy)γ-射线辐射花粉两种方法诱导小麦(Triticum aestixum L)-滨麦(Leymus mollis Trin)和小麦-中间偃麦草[Thinopyrum intermedium(Host)Barkwarth]的易位系。通过基因组原位杂交(GISH)分析,在59个小滨麦代换系M8724-8-13与离果山羊草(Aegilops trincialis L)3C染色体附加系的杂交后代中获得了3株小麦-滨麦易位系,易位频率达到5.08%。其中1个易位系经C-分带证明是小麦的7D染色体与1条滨麦的染色体发生了整臂易位。同时还获得了3个滨麦染色体的缺失系。滨麦染色体发生结构变异的总频率为8.47%。除了滨麦染色体以外,在一些植株中还观察到小麦的染色体也发生了缺失。在69个普通小麦与小麦-中间偃麦草附加系TAI-14辐射花粉的杂交后代中,得到2株小麦-中间偃麦草的易位系,易位频率为2.90%。两个易位系都是小片段易位,经C-分带证明两个易位系所涉及的小麦染色体分别是3A和4A。利用杀配子染色体和低剂量γ射线辐射花粉诱导小麦异源易位系都是行之有效的方法,但这两种方法各有优缺点,在实际工作中应根据不同的目的选用不同的实验体系。 相似文献
3.
普通小麦与东方旱麦草异附加系和异代换系的选育与原位杂交检测 总被引:10,自引:0,他引:10
旱麦草属(Eremopyrum)是用于小麦品种改良的又-潜在的植物资源。为了筛选小麦-旱麦草异附加系、异代换系,对普通小麦品种 Fukoho×东方旱麦草属间杂种的 BC2F3代材料的96粒种子进行了染色体数目的检测,共检出15粒2n=43的种子, 8粒 2n= 44的种子,进一步对以上材料进行的基因组DNA原位杂交,共鉴定出3个单体附加系,2个二体附加系,1个双单体附加,1个小麦三体单体附加,1个附加3条东方旱麦草染色体的小麦单体,在染色体数为42的个体中,检测出1个单体代换,1个双单体代换。根据BC2F3代自交品系来源的不同,初步认为由双单体附加自交比单体附加自交选择异附加系的效率高。 相似文献
4.
By chromosome C-banding and bi-color fluorescence in situ hybridization (FISH) using digoxigenin-labelled total genomic DNA of Leymus racemosus (Lam.) Tzvel. and biotinylated total genomic DNA of Haynaldia villosa (L.) Schur as probes, three wheat-alien lines with L. racemosus Lr.7 addition and H. villosa 6VS/6AL translocated chromosomes, and eight lines with L. racemosus Lr.14 addition and H.villosa 6VS/6AL translocated chromosomes were respectively identified from DALr.7×T6VS/6AL (93G51-4×P64) and DALr.14×T6VS/6AL (94G15×P64)F2 or F3 hybrids. Fluorescein-isothiocyanate-conjugated avidin and rhodamine-conjugated sheep anti-digoxigenin Fab fragment were used in bi-color FISH detection. The chromosomes of L.racemosus and 6VS fragment of H. villosa were simultaneously detected by their red and green fluorescence. Powdery mildew and scab resistance were also evaluated. The result showed that the obtained plants had high resistance to these two diseases. The potential usage of bi-color FISH in identifying chromatin of L.racemosus and H.villosa was discussed. 相似文献
5.
6.
Systematic Reverse Genetics of Transfer-DNA-Tagged
Lines of
Arabidopsis
: Isolation of Mutations in the Cytochrome P450 Gene Superfamily 总被引:6,自引:0,他引:6 下载免费PDF全文
Rodney G. Winkler Michael R. Frank David W. Galbraith René Feyereisen Kenneth A. Feldmann 《Plant physiology》1998,118(3):743-750
We have developed an efficient reverse-genetics protocol that uses expedient pooling and hybridization strategies to identify individual transfer-DNA insertion lines from a collection of 6000 independently transformed lines in as few as 36 polymerase chain reactions. We have used this protocol to systematically isolate Arabidopsis lines containing insertional mutations in individual cytochrome P450 genes. In higher plants P450 genes encode enzymes that perform an exceptionally wide range of functions, including the biosynthesis of primary metabolites necessary for normal growth and development, the biosynthesis of secondary products, and the catabolism of xenobiotics. Despite their importance, progress in assigning enzymatic function to individual P450 gene products has been slow. Here we report the isolation of the first 12 such lines, including one (CYP83B1-1) that displays a runt phenotype (small plants with hooked leaves), and three insertions in abundantly expressed genes. The DNAs used in this study are publicly available and can be used to systematically isolate mutants in Arabidopsis. 相似文献
7.
8.
9.
Quality control mechanisms during protein synthesis are essential to
fidelity and cell survival. Leucyl-tRNA synthetase (LeuRS) misactivates
non-leucine amino acids including isoleucine, methionine, and norvaline. To
prevent translational errors, mischarged tRNA products are translocated
30Å from the canonical aminoacylation core to a hydrolytic
editing-active site within a completely separate domain. Because it is
transient, the tRNA translocation mechanism has been difficult to isolate. We
have identified a “translocation peptide” within Escherichia
coli LeuRS. Mutations in the translocation peptide cause tRNA to
selectively bypass the editing-active site, resulting in mischarging that is
lethal to the cell. This bypass mechanism also rescues aminoacylation of an
editing site mutation that hydrolyzes correctly charged
Leu-tRNALeu. Thus, these LeuRS mutants charge tRNALeu
but fail to translocate these products to the hydrolytic site, where they are
cleared to guard against genetic code ambiguities.Quality control during translation depends on the family of aminoacyl-tRNA
synthetases (aaRSs),2
which is responsible for the first step of protein synthesis. Each aaRS
selectively aminoacylates just one of the 20 standard amino acids to its
cognate tRNA (1). About half of
this family of enzymes ensures fidelity by employing a “double sieve
model” that relies on two active sites
(2,
3). One sieve is synthetic and
produces charged tRNA. The other is a hydrolytic editing-active site that
clears mistakes. Defects in the editing mechanism cause cell death
(4,
5) and also neurological
disease in mammals (6).The aminoacylation site in the ancient canonical core of the aaRS activates
its cognate amino acid but can also misactivate structurally similar amino
acids (1). The editing-active
site blocks the correctly charged amino acid
(7,
8) and hydrolyzes mischarged
amino acids from the tRNA. Amino acid editing destroys mistakes before they
can be incorporated by the ribosome, which would result in the production of
statistical proteins (1).Amino acid proofreading requires that the charged tRNA transiently migrates
between two enzyme domains that are responsible for aminoacylation and
editing. For leucyl-tRNA synthetase (LeuRS) and the homologous
isoleucyl-(IleRS) and valyl-tRNA synthetases (ValRS), the editing domain
resides in a structural insertion called CP1
(9) that splits the Rossmann
ATP binding fold. The insert folds independent of the canonical core
(10–12).
The isolated CP1 domains from LeuRS, ValRS, and IleRS can independently and
specifically hydrolyze mischarged amino acid from its cognate tRNA
(13–15).The aminoacylation and editing-active sites of LeuRS are separated by about
30 Å. Thus, the charged 3′ end of the tRNA must be faithfully
translocated a significant distance for proofreading and then hydrolysis if it
is mischarged (16). It has
also been suggested that the tRNA 3′ end binds initially near the
editing-active site and requires translocation to the aminoacylation site
(17).We hypothesized that flexible molecular hinges might facilitate
conformational changes between the aminoacylation and the editing complexes
(18). Two putative hinge sites
were predicted by computational analysis of Thermus thermophilus
LeuRS. One hinge at Ser-227 was located in the N-terminal β-strand that
links the aminoacylation and CP1 editing domains
(18). Mutations at the
predicted hinge site in the β-strand linker of Escherichia coli
LeuRS abolished aminoacylation activity and significantly decreased amino acid
editing activity (18).A second hinge site at Glu-393 was identified in a flexible peptide within
the CP1 domain of T. thermophilus LeuRS
(18). Here, we describe
results at a homologous Asp-391 site in E. coli LeuRS that
demonstrate that this hinge comprises a portion of a translocation peptide.
Unlike the predicted β-strand hinge mutation, the aminoacylation and
editing activities of the CP1 domain-based hinge mutants in LeuRS were intact.
Surprisingly however, mutations within the translocation peptide yield
mischarged tRNA despite a robust deacylation activity. We hypothesize that
impairing the LeuRS translocation peptide causes the charged tRNA 3′ end
to bypass the editing sieve prior to product release. Defects in the
translocation peptide and its mechanism result in amino acid toxicities that
are lethal to the cell. 相似文献
10.
LIU Jin-Yuan TAO Wen-Jing LIU Da-Jun CHEN Pei-Du LI Wan-Long XIANG Qi-Jun DUAN Xia-Yu 《植物学报(英文版)》1999,41(10)
Fa plants from Yang94-138 ×92R149 were analyzed using species-specific probe pHv62 for Haynaldia villosa (L.) Schur and RFLP probe Psrll3 located on the short ann of homoeologous group six for wheat ( Triticum aestivum L. ). The results showed that the transmission rate of 6VS in the F2 was 69.5 %, which was close to the expected value of 75%. 147 F2 plants from the above Fl plant were tested for their resistance in seedling stage to 6 pathogenic strains of powdery mildew. It was observed that Pm21 genes on 6VS inherited dominantly and expressed well when transferred to wheat-"Yangmai 158" genotype. 相似文献
11.
小麦—大赖草易位系的RFLP分析 总被引:4,自引:0,他引:4
利用辐射、花药培养及杀配子基因效应已创制出一系列小麦-大赖草易位系.为在其中找出可能的纯合易位系、明确易位所涉及的相关染色体以及易位断裂点的确切位置,利用了已被定位于小麦7个部分同源群染色体长、短两臂上的67个探针进行了RFLP分析,结果鉴定出3个纯合的易位系:T1BL*7Lr#1S、T4BS*4BL-7Lr#1S和T6AL*7Lr#1S.其中,易位系T1BL*7Lr#1S和T6AL*7Lr#1S中染色体7Lr#1的断裂点位于标记MWG808和标记ABG476.1之间,而1B和6A染色体上的断裂点都在着丝粒附近.易位系T4BS*4BL-7Lr#1S中染色体7L#1的断裂点位于标记BCD349和标记CDO595之间,4B染色体断裂点则位于标记CDO541和标记PSR164之间的长臂上. 相似文献
12.
13.
14.
Bryson W. Katona Shrikant Anant Douglas F. Covey William F. Stenson 《The Journal of biological chemistry》2009,284(5):3354-3364
Bile acids are steroid detergents that are toxic to mammalian cells at high
concentrations; increased exposure to these steroids is pertinent in the
pathogenesis of cholestatic disease and colon cancer. Understanding the
mechanisms of bile acid toxicity and apoptosis, which could include
nonspecific detergent effects and/or specific receptor activation, has
potential therapeutic significance. In this report we investigate the ability
of synthetic enantiomers of lithocholic acid (ent-LCA),
chenodeoxycholic acid (ent-CDCA), and deoxycholic acid
(ent-DCA) to induce toxicity and apoptosis in HT-29 and HCT-116
cells. Natural bile acids were found to induce more apoptotic nuclear
morphology, cause increased cellular detachment, and lead to greater capase-3
and -9 cleavage compared with enantiomeric bile acids in both cell lines. In
contrast, natural and enantiomeric bile acids showed similar effects on
cellular proliferation. These data show that bile acid-induced apoptosis in
HT-29 and HCT-116 cells is enantiospecific, hence correlated with the absolute
configuration of the bile steroid rather than its detergent properties. The
mechanism of LCA- and ent-LCA-induced apoptosis was also investigated
in HT-29 and HCT-116 cells. These bile acids differentially activate initiator
caspases-2 and -8 and induce cleavage of full-length Bid. LCA and
ent-LCA mediated apoptosis was inhibited by both pan-caspase and
selective caspase-8 inhibitors, whereas a selective caspase-2 inhibitor
provided no protection. LCA also induced increased CD95 localization to the
plasma membrane and generated increased reactive oxygen species compared with
ent-LCA. This suggests that LCA/ent-LCA induce apoptosis
enantioselectively through CD95 activation, likely because of increased
reactive oxygen species generation, with resulting procaspase-8 cleavage.Bile acids are physiologic steroids that are necessary for the proper
absorption of fats and fat-soluble vitamins. Their ability to aid in these
processes is largely due to their amphipathic nature and thus their ability to
act as detergents. Despite the beneficial effects, high concentrations of bile
acids are toxic to cells
(1-11).
High fat western diets induce extensive recirculation of the bile acid pool,
resulting in increased exposure of the colonic epithelial cells to these toxic
steroids (12,
13). A high fat diet is also a
risk factor for colon carcinogenesis; increased bile acid exposure is
responsible for some of this risk. Bile acids can contribute to both colon
cancer formation and progression, and their effects on colonic proliferation
and apoptosis aid this process by disrupting the balance between cell growth
and cell death, as well as helping to select for bile acid-resistant cells
(14,
15).In colonocyte-derived cell lines bile acid-induced apoptosis is thought to
proceed through mitochondrial destabilization with resulting mitochondrial
permeability transition formation and cytochrome c release as well as
generation of oxidative stress
(1,
9-11).
Bile acid-induced apoptosis has also been extensively explored in hepatocyte
derived cell lines with mechanisms including mitochondria dysfunction
(16-23),
endoplasmic reticulum stress
(24), ligand-independent
activation of death receptor pathways
(18,
25-28),
and modulation of cellular apoptotic and anti-apoptotic Bcl-2 family proteins
(29).Although ample evidence exists for multiple mechanisms of bile acid-induced
apoptosis, the precise interactions responsible for initiating these apoptotic
pathways are still unclear. Bile acids have been shown to interact directly
with specific receptors (30,
31). These steroids can also
initiate cellular signaling through nonspecific membrane perturbations
(32), and evidence exists
showing that other simple detergents (i.e. Triton X-100) are capable
of inducing caspase cleavage nonspecifically with resultant apoptosis
(33). Therefore, hydrophobic
bile acids may interact nonspecifically with cell membranes to alter their
physical properties, bind to receptors specific for these steroids, or utilize
a combination of both specific and nonspecific interactions to induce
apoptosis.Bile acid enantiomers could be useful tools for elucidating mechanisms of
bile acid toxicity and apoptosis. These enantiomers, known as
ent-bile acids, are synthetic nonsuperimposable mirror images of
natural bile acids with identical physical properties except for optical
rotation. Because bile acids are only made in one absolute configuration
naturally, ent-bile acids must be constructed using a total synthetic
approach. Recently we reported the first synthesis of three enantiomeric bile
acids: ent-lithocholic acid
(ent-LCA),2
ent-chenodeoxycholic acid (ent-CDCA), and
ent-deoxycholic acid (ent-DCA)
(Fig. 1)
(34,
35). Enantiomeric bile acids
have unique farnesoid X receptor, vitamin D receptor, pregnane X receptor, and
TGR5 receptor activation profiles compared with the corresponding natural bile
acids (34). This illustrates
that natural and enantiomeric bile acids interact differently within chiral
environments because of their distinct three-dimensional configurations
(Fig. 1). Despite these
differences in chiral interactions, ent-bile acids have physical
properties identical to those of their natural counterparts including
solubility and critical micelle concentrations
(34,
35). With different receptor
interaction profiles and identical physical properties compared with natural
bile acids, ent-bile acids are ideal compounds to differentiate
between the receptor-mediated and the non-receptor-mediated functions of
natural bile acids.Open in a separate windowFIGURE 1.Natural and enantiomeric bile acids. Structures and
three-dimensional projection views of natural LCA, CDCA, DCA, and their
enantiomers (ent-LCA, ent-CDCA, and ent-DCA). The
three-dimensional ent-steroid structure is rotated 180° around
the long axis for easier comparison with the natural steroid.In this study we explore the enantioselectivity of LCA-, CDCA-, and
DCA-mediated toxicity and apoptosis in two human colon adenocarcinoma cell
lines, HT-29 and HCT-116. Because the mechanism of natural LCA induced
apoptosis has never been characterized, we then examined in more detail LCA-
and ent-LCA-mediated apoptosis in colon cancer cells. These studies
will not only explore the LCA apoptotic mechanism but will also determine
whether ent-LCA signals through similar cellular pathways. 相似文献
15.
Jacob M. Dundee Mar Puigdellívol Richard Butler Thomas O. J. Cockram Guy C. Brown 《Aging cell》2023,22(2)
Aging causes loss of brain synapses and memory, and microglial phagocytosis of synapses may contribute to this loss. Stressed neurons can release the nucleotide UTP, which is rapidly converted into UDP, that in turn activates the P2Y6 receptor (P2Y6R) on the surface of microglia, inducing microglial phagocytosis of neurons. However, whether the activation of P2Y6R affects microglial phagocytosis of synapses is unknown. We show here that inactivation of P2Y6R decreases microglial phagocytosis of isolated synapses (synaptosomes) and synaptic loss in neuronal–glial co‐cultures. In vivo, wild‐type mice aged from 4 to 17 months exhibited reduced synaptic density in cortical and hippocampal regions, which correlated with increased internalization of synaptic material within microglia. However, this aging‐induced synaptic loss and internalization were absent in P2Y6R knockout mice, and these mice also lacked any aging‐induced memory loss. Thus, P2Y6R appears to mediate aging‐induced loss of synapses and memory by increasing microglial phagocytosis of synapses. Consequently, blocking P2Y6R has the potential to prevent age‐associated memory impairment. 相似文献
16.
M. E. Zirakparvar 《Journal of nematology》1982,14(2):217-220
Population increase of Pratylenchus hexincisus on 41 soybean cultivars (maturity groups I-VI) and lines was tested under greenhouse conditions. After 3 months, P. hexincisus was recovered from the roots of all plants tesled. Final populations of P. hexincisus per pot were larger than the initial population in 13 cultivars. Pathogenicity of P. hexincisus on five soybean cultivars representing maturity groups (I-V) was demonstrated under greenhouse conditions. An inoculmn of 5,000 P. hexineisus/plant significantly decreased the root and shoot biomass of all five soybean cultivars after 3 months. 相似文献
17.
小偃麦部分双二倍体及其异附加系异源染色体的GISH分析 总被引:7,自引:0,他引:7
应用TISH对小偃麦部分双二倍体TAF46(2n=8x=56)及其衍生的6个二体异附加系的中间偃麦草染色体组种类进行了分析、鉴定。以拟鹅冠草(Ps.strigosa)DNA为探针的分析结果表明,TAF46所含有的中间偃麦草染色体组为合成染色体组,即6条St组染色体和8条E组染色体。在其衍生的二体异附加系中,L4和L7含有St组染色体,L1、L2、L3、L5含有E组染色体。TAF46所含有的中间偃麦草染色体的部分同源群依次为IE(L3)、2St(L6)、3E(L2)、4St(L4)、5E(L5)、6St(L7)、7E(L1)。 相似文献
18.
In vitro studies conducted in Aplysia and chick sensory neurons indicate that in addition to microtubule assembly, long microtubules in the C-domain of the growth cone move forward as a coherent bundle during axonal elongation. Nonetheless, whether this mode of microtubule translocation contributes to growth cone motility in vivo is unknown. To address this question, we turned to the model system Drosophila. Using docked mitochondria as fiduciary markers for the translocation of long microtubules, we first examined motion along the axon to test if the pattern of axonal elongation is conserved between Drosophila and other species in vitro. When Drosophila neurons were cultured on Drosophila extracellular matrix proteins collected from the Drosophila Kc167 cell line, docked mitochondria moved in a pattern indicative of bulk microtubule translocation, similar to that observed in chick sensory neurons grown on laminin. To investigate whether the C-domain is stationary or advances in vivo, we tracked the movement of mitochondria during elongation of the aCC motor neuron in stage 16 Drosophila embryos. We found docked mitochondria moved forward along the axon shaft and in the growth cone C-domain. This work confirms that the physical mechanism of growth cone advance is similar between Drosophila and vertebrate neurons and suggests forward translocation of the microtubule meshwork in the axon underlies the advance of the growth cone C-domain in vivo. These results highlight the need for incorporating en masse microtubule translocation, in addition to assembly, into models of axonal elongation. 相似文献
19.
小麦新种质4844中外源P染色质的GISH与SSR分析 总被引:6,自引:1,他引:6
采用基因组原位杂交(GISH)检测和染色体组成分析方法,对大穗多花小麦新种质4844后代的15个株系进行遗传分析。结果发现,4844-12是1个稳定的异附加系,4844-2和4844-8是稳定的异代换系;对异代换系进行SSR分析表明,代换系中小麦的6D染色体被1对P染色体代换,说明这对冰草染色体与小麦6D染色体有部分同源关系,由此确定4844中的冰草染色体为6P;同时筛选出冰草6P染色体的4个SSR标记。 相似文献
20.
Characterization of Cadmium Binding, Uptake, and Translocation in
Intact Seedlings of Bread and
Durum Wheat Cultivars 总被引:31,自引:1,他引:31 下载免费PDF全文
Jonathan J. Hart Ross M. Welch Wendell A. Norvell Lori A. Sullivan Leon V. Kochian 《Plant physiology》1998,116(4):1413-1420
High Cd content in durum wheat (Triticum turgidum L. var durum) grain grown in the United States and Canada presents potential health and economic problems for consumers and growers. In an effort to understand the biological processes that result in excess Cd accumulation, root Cd uptake and xylem translocation to shoots in seedlings of bread wheat (Triticum aestivum L.) and durum wheat cultivars were studied. Whole-plant Cd accumulation was somewhat greater in the bread wheat cultivar, but this was probably because of increased apoplastic Cd binding. Concentration-dependent 109Cd2+-influx kinetics in both cultivars were characterized by smooth, nonsaturating curves that could be dissected into linear and saturable components. The saturable component likely represented carrier-mediated Cd influx across root-cell plasma membranes (Michaelis constant, 20–40 nm; maximum initial velocity, 26–29 nmol g−1 fresh weight h−1), whereas linear Cd uptake represented cell wall binding of 109Cd. Cd translocation to shoots was greater in the bread wheat cultivar than in the durum cultivar because a larger proportion of root-absorbed Cd moved to shoots. Our results indicate that excess Cd accumulation in durum wheat grain is not correlated with seedling-root influx rates or root-to-shoot translocation, but may be related to phloem-mediated Cd transport to the grain. 相似文献